[GRASSLIST:10558] Re: TOPIDX flow direction algorithm

[Dylan Beaudette]

On Friday 24 February 2006 07:31 am, twiens wrote:
> I'm working with some ArcGIS users and in a note in the AML
> script to calculate the topographic index, the author notes
> that ArcInfo uses a D8 algorithm to calculate the
> contributing area. The concern is that for relatively flat
> areas, the index value will be inaccurate or inappropriate.
> I've noted in areas that I have generated a topographic
> index, that flat areas seem to be set to NULL by topidx.
>
> I've not been able to find any reference to this issue in
> the topidx documentation. Can someone tell me if this
> concern is valid for r.topidx?
>
> Thanks
>
> T
> --
> Trevor Wiens
> twiens at interbaun.com

I would highly recommend enabling c++ support when you compile GRASS, so that 
you have access to the r.terraflow . This will compute a TCI, and in many 
cases I have found the output from r.terraflow to be superior to the 
analogous commands in GRASS.

cheers,


-- 
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341